're carrying twins. if that were to be the case, what would that do of the succession? >> well, it would really be a case of which child appeared first. and it makes no difference now with this new law. it hasn't been passed yet. but they're going to rush it through. whatever the first born is, whether it's male or female, the first born will be in line for the throne. it's that simple. >> it's very exciting news, indeed. and all of our thoughts and prayers are with kate. >> now, i'm absolutely -- now, diana, funny enough, paved the way with this morning sickness. she had terrible morning sickness. the royal family had never heard of it. and she was saying once again, diana's there, paving the way for kate. >> yes. ingrid, we thank you so much. we'll have more to come from here in london. elizabeth? >> lara, thank you so much. >>> let's find out more about this condition called hyperemesis, that kate has been hospitalized with. abc news senior medical contributor dr. jennifer ashton is an obgyn. you've treated lots of expectant moms. people are causing this extreme nausea and morning sickness.